Distortional composite matrix

ABSTRACT

The disclosure relates to composites having increased distortional deformation, and/or decreased dilatation load, as expressed within the von Mises strain relationship, which provide increased von Mises strain results. These composites may provide enhanced composite mechanical performances.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional application of, and claiming priority, to U.S.application Ser. No. 11/613,667, filed on Dec. 20, 2006 and tilted NewDistortional Composite Matrix, which claims priority to provisional U.S.Application Ser. No. 60/753,597, filed on Dec. 22, 2005, and titled NewDistortional Composite Matrix, both of which are hereby incorporated byreference.

BACKGROUND OF THE DISCLOSURE

A wide variety of composite structures exist. Many of these compositestructures display low distortion load, high dilatation load, and lowvon Mises strain results. Composites having low von Mises strain resultsmay limit the performance of the composite, such as by having lowstrength, high weight, and/or experiencing other types of problems.

A composite, and/or process for forming such a composite, is neededwhich may solve or reduce one or more problems associated with one ormore of the prior art composites and/or methods.

SUMMARY OF THE DISCLOSURE

In one aspect of the disclosure, a composition comprises a DEN431substance and a 33DDS substance. The DEN431 substance comprises aBisphenol F based tri-functional novolac epoxy resin, and the 33DDSsubstance comprises a 3,3′ diaminodiphenylsulfone.

In another aspect of the disclosure, a composition comprises a DEN431substance with a metaBAPS substance. The DEN431 substance comprises aBisphenol F based tri-functional novolac epoxy resin, and the metaBAPSsubstance comprises a 4,4′ bis(3-aminophenoxy)diphenylsulfone.

In a further aspect of the disclosure, a composition comprises aTactix123 substance and a 33DDS substance. The Tactix123 substancecomprises a diglycidyl ether of Bisphenol-A, and the 33DDS substancecomprises a 3,3′ diaminodiphenylsulfone.

In another aspect of the disclosure, a composition comprises a DEN431substance with an APB133 substance. The DEN431 substance comprises aBisphenol F based tri-functional novolac epoxy resin, and the APB133substance comprises a 1,3 bis(3-aminophenoxy)benzene.

In yet another aspect of the disclosure, a composition comprises asubstance made of diglycidyl α,α′-bis(4-hydroxyphenyl)-p-diisopropylbenzene (Bis M) with a metaBAPSsubstance. The metaBAPS substance comprises a 4,4′bis(3-aminophenoxy)diphenylsulfone.

In a further aspect of the disclosure, a composition comprises asubstance made of 1,3 bis(4-aminophenoxy)-2, 2 dimethylpropane with aTactix123 substance. The Tactix123 substance comprises a diglycidylether of Bisphenol-A.

In an additional aspect of the disclosure, a composition comprises asubstance made of 1,3 bis(3-aminophenoxy)-2, 2 dimethylpropane with aTactix123 substance. The Tactix123 substance comprises a diglycidylether of Bisphenol-A.

In another aspect of the disclosure, a composition is provided which wasdesigned to have higher distortional loads and lower dilatation loads inorder to increase von Mises strain.

In still another aspect of the disclosure, a method is provided forforming a composition having increased von Mises strain. The methodcomprises combining an amine and an epoxy in order to increasedistortional load and lower dilatation load.

These and other features, aspects and advantages of the disclosure willbecome better understood with reference to the following drawings,description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a perspective view of a cube showing the volume expansionof the cube upon the application of force.

FIG. 2 depicts a perspective view of the cube of FIG. 1 upon theapplication of a biased strain to the cube.

FIG. 3 depicts a table which shows von Mises strain for a series ofdi-glycidyl epoxies which demonstrates one of the theories of thedisclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

The following detailed description is of the best currently contemplatedmodes of carrying out the disclosure. The description is not to be takenin a limiting sense, but is made merely for the purpose of illustratingthe general principles of the disclosure, since the scope of thedisclosure is best defined by the appended claims.

It has been discovered that a composite polymeric matrix with improved(i.e. increased) distortional deformation, and/or decreased (i.e. lower)dilatation load, as expressed with the von Mises strain relationship,will increase von Mises strain and provide enhanced composite mechanicalperformance. The instant disclosure provides novel compositions, andmethods for their formulation, which provide increased distortionaldeformation, and/or decreased dilatation load, in order to increase vonMises strain within the composition.

The deformation of matter can be divided into two categories: dilatationor volume expansion and distortion. The mechanisms correspond to theelastic and plastic processes occurring in matter under a uniform stateof stress. Forces applied to a physical system that result in a volumechange are termed elastic and have been adequately described usingHooke's Law. Volume expansion as shown in FIG. 1, is a result of a localloss of intermolecular cohesion and a reduction of density. As long asthe displacements are small, the linear restoring force or cohesivestrength will reverse the effects on release of the applied force. Thecohesive forces in question are also responsible for the thermalcontraction with temperature and a direct consequence of the decrease inamplitude of the molecular vibrations as the polymer is cooled. Thecohesive forces can be described using a potential function whichrelates the intermolecular energy of attraction and the separationdistance to van der Waals forces and nearest neighbor repulsions.

At a macroscopic level, an isotropic body deforming elastically willexpand conforming to the following relations: ε_(v)=J₁+J₂+J₃, whereJ₁=ε₁+ε₂+ε₃, J₂=ε₁ε₂+ε₂ε₃+ε₃ε₁, J₃=ε₁ε₂ε₃, and ε₁, ε₂, and ε₃ are theprincipal strains. The volume change can be approximated by the firstinvariant of strain J₁, which represents over 98% of the volume change.

The critical volume expansion capacity is numerically equal to theamount of contraction experienced by the polymer on cooling from it'sglass temperature. The thermal contraction that is directly relatable tothe reduction in thermal energy and the decrease in the equilibriumintermolecular distance represents the maximum elastic expansionpotential under mechanical or thermal loading.

It is reasonable to view distortion or a deviatoric response of amaterial to an applied force as an abrupt shear transformation orcooperative motion of a specific volume or segment of the polymer chainresponding to a strain bias. The distorted cube illustrated in FIG. 2 isa simple depiction of a distortional process.

The von Mises strain can be determined using the following equation,with the input quantities being the three principal strains:

$ɛ_{vM} = \left\{ {\frac{1}{2}\left\lbrack {\left( {ɛ_{1} - ɛ_{2}} \right)^{2} + \left( {ɛ_{2} - ɛ_{3}} \right)^{2} + \left( {ɛ_{1} - ɛ_{3}} \right)^{2}} \right\rbrack} \right\}^{\frac{1}{2}}$

Polymers within composites can and are often subjected to a forceapplication that severely limits their ability to flow. The constraintimposed by fiber orientations greater than approximately 30° to theprincipal strain direction will generate a dilatational criticaldeformation. The lamina orientations with angle differentials less thanapproximately 25° to the direction of global strain will transition froma dilatational to a distortional critical behavior.

Our enhanced understanding of the constituent materials deformationbehavior has enabled us to design structure that can take advantage ofthe unique performance characteristics of composite materials. Analysisand test validation has shown that mechanical loading that favors matrixdistortion rather than dilatation allows for a composite structurespecific performance capability. Particular constituent materialsultimate strengths however can limit the achievement of maximumperformance. For example, our testing shows that fiber performance islimited by a low matrix critical distortional capability of thethermoset resins used today. Our study of strength critical structurehas compared the present design and construction approach with a matrixdistortional dominated design approach. We studied a commercialtransport category wing and fuselage. The weight savings potentialoffered by a composite with increased von Mises strain capability may beapproximately 15 percent for the fuselage structure and 30% for the wingstructure.

Using a combination of computer simulation and experimental chemicalformulation, a number of epoxy-amine formulations (such as formulationscomprising at least one diamine and at least one epoxy resin asdisclosed herein) have been identified that exhibit an increase in vonMises strain with respect to many existing commercially availablematerials. The formulation methodology attempted to improve von Misesstrain by selecting chemical structures that contained certain keymolecular features and maximized the amount used within the constraintsof a production handle-able product form. The specific amine structuresselected have organic portions that contribute substantially to theoverall system distortion. They have been selected for their alternatingstiff phenyl rings and rotating sp³ bond hybridization centers such asether, methylene, isopropyl or sulfone groups that allow the aminemoiety to interrogate numerous torsional configurations when subjectedto externally applied loads. The conformations considered are specificspatial arrangements of atoms or groups of the molecule inasmuch as thearrangements are determined by a specification of the torsion angles.The epoxy components previously available do not have similarconfigurations and have historically been selected because they areliquids and as such impart tack for ease of handling to the finalformulation.

The measurement of von Mises strain requires fabrication and testing ofa composite lamina. The fiber orientation of the test coupon may be setto 10 degrees with respect to the load application direction. The strainat failure as defined by catastrophic fracture may be recorded andanalyzed using a commercial Finite Element Analysis code fordetermination of the maximum value of the principle strains within thebody of the specimen at the instant of failure. The principle strainsmay then be used as input values to the von Mises equation fordetermination of the critical von Mises strain.

From our testing and computer simulations, the specific compositionswhich have exhibited improvements in von Mises strain include thefollowing compositions: (1) a DEN431 substance with a 33DDS substance;(2) a DEN 431 substance with a metaBAPS substance; (3) a Tactix123substance with a 33DDS substance; (4) a DEN431 substance with an APB133substance; (5) a diglycidyl α,α′-bis(4-hydroxyphenyl)-p-diisopropylbenzene (Bis M) substance with ametaBAPS substance; (6) a 1,3 bis(4-aminophenoxy)-2, 2 dimethylpropanesubstance with a Tactix123 substance; and (7) a 1,3bis(3-aminophenoxy)-2, 2 dimethylpropane substance with a Tactix123substance.

The DEN431 substance comprises a Bisphenol F based tri-functionalnovolac epoxy resin. The metaBAPS substance comprises a 4,4′bis(3-aminophenoxy)diphenylsulfone substance. The Tactix123 substancecomprises a diglycidyl ether of Bisphenol-A substance. The 33DDSsubstance comprises a 3,3′ diaminodiphenylsulfone substance. The APB133substance comprises a 1,3 bis(3-aminophenoxy)benzene substance. Itshould be noted that the following substances are epoxies: DEN431;Tactix123; and diglycidyl α,α′-bis(4-hydroxyphenyl)-p-diisopropylbenzene (Bis M). Similarly, itshould be noted that the following substances are amines: 33DDS;metaBAPS; APB133; 1,3 bis(4-aminophenoxy)-2, 2 dimethylpropane; and 1,3bis(3-aminophenoxy)-2, 2 dimethylpropane.

The molecular basis for a polymer matrix ability to undergo a deviatoricresponse to an applied force is theorized as due to a cooperative motionof a specific volume or segment of the polymer chain. The molecularmotions or dynamics of the polymer structure includes vibrational, bondbending and conformational rearrangement that can be considered asindependent processes. The scale of the segmental dynamics may bedetermined by the local molecular environment, and the number and energybarriers to conformational rearrangements. The local environment may belimited to the scale established by the crosslinks formed duringpolymerization.

Simulations of these processes indicates that macroscopic loading ismanifested at the molecular level as a continual disappearance of alocal energy minimum due to the conformational rearrangement followed byrelaxation to a new minimum. The potential energy hypersurface thatrepresents the condition describes the glassy material as a distributionof energy minima in phase space, with maxima and saddle points thatdefine the system dynamics. Because strain or deformation is anintensive quantity—it is proportional to the fraction of the systeminvolved in the relaxation to a new energy minimum. Therefore moremolecular structures which are able to undergo conformationalexploration will enhance the polymer's ability to undergo an increasedmacroscopic distortional response. In addition, based on the intensivenature of deformation, using a volumetric argument for quantifyingindividual ingredient improvement potential has also been found to bevalid.

Both experimental data and computer simulations have indicated that thepolymer formulation should aim to maximize possible backbone rotationalconformations with a structure optimized for exploration of dihedralconformations to maximize energy dissipation. Required features includealternating stiff phenyl rings and rotating sp³ bond hybridizationcenters such as ether, methylene, isopropyl or sulfone groups that allowthe molecule to interrogate numerous torsional configurations. Use ofdifunctional epoxies containing linked sp³ centers such as Tactix177 onthe other hand, have not performed as well as the alternating stiff andfree rotation configurations. Meta rather than para substitution on thephenyl rings has been qualitatively seen as a means to increase thepossible number of potential conformers.

FIG. 3 provides a table which shows von Mises strain for a series ofdi-glycidyl epoxies. DEN431 is provided in the table for reference. Theresults demonstrate that by adding substances to the chain, increasedvon Mises strain results may occur. For instance, phenyl has a von Misesstrain of 0.068, while phenyl-isopropyl-phenyl has a von Mises strain of0.237, and phenyl-isopropyl-phenyl-isopropyl-phenyl has a von Misesstrain of 0.386. These results demonstrate the validity of the theory ofthe instant disclosure.

A typical prior art composition is SOTA System with IM-7 which testinghas shown has a von Mises strain of approximately 0.19, which is afairly typically von Mises strain result for the prior art compositions.State of the art epoxy resin formulations for composites are usuallycommercial trade secrets but a typical generic formulation would consistof an epoxy such as MY721 or tetraglycidyl 4,4′-diamino diphenylemthaneand 44DDS or 4,4′-diaminodiphenylsulfone mixed in a ratio of about 20 to40% by weight of amine to epoxy. A typical von Mises strain value for aformulation such as this is in the range of 0.15 to 0.19. All seven ofthe new compositions disclosed under this disclosure have substantiallyimproved von Mises strain results, as set forth below, which arecompletely unexpected over the prior art.

For instance, experimental results have shown that the composition ofDEN431 mixed with 33DDS has a von Mises strain of 0.295 with an amineweight percent content of 28% to 0.345 with an amine weight content of52%. The 28% formulation represents a 1:1 stoichiometry ratio.

Experimental results have shown that the composition of DEN431 mixedwith mBAPS has a von Mises strain of 0.322 with an amine weight percentcontent of 41% to 0.342 with an amine weight content of 65%. The 41%formulation represents a 1:1 stoichiometry ratio.

Experimental results have shown that the composition of Tactix123 mixedwith 33DDS has a von Mises strain of 0.294 with an amine weight percentcontent of 27% to 0.345 with an amine weight content of 43%. The 27%formulation represents a 1:1 stoichiometry ratio.

Experimental results have shown that the composition of DEN431 mixedwith APB133 has a von Mises strain of 0.313 with an amine weight percentcontent of 32% to 0.37 with an amine weight content of 56%. The 32%formulation represents the 1:1 stoichiometry ratio.

Experimental results have shown that the composition of diglycidyl α,α′-bis(4-hydroxyphenyl)-p-diisopropylbenzene (Bis M) mixed with metaBAPShas a von Mises strain of 0.41 with an amine weight percent content of24% to 0.42 with an amine weight percent content of 32%. The 32% weightcontent formulation is the 1:1 stoichiometry mixture.

Computer simulations have shown that the composition of 1,3bis(4-aminophenoxy)-2, 2 dimethylpropane mixed with Tactix123 epoxy,with a 1:1 stoichiometric ratio of 30% by weight amine with 70% byweight epoxy, has a von Mises strain of 0.31.

Computer simulations have shown that the composition of 1,3bis(3-aminophenoxy)-2, 2 dimethylpropane mixed with Tactix123 epoxy,with a 1:1 stoichiometric ratio of 30% by weight amine with 70% byweight epoxy, has a von Mises strain of 0.32.

In another embodiment of the disclosure, a composition is provided whichwas designed to have higher distortional loads and lower dilatationloads in order to increase von Mises strain. In one embodiment, thecomposition may have a von Mises strain of at least 0.300. In anotherembodiment, the may have a von Mises strain of at least 0.400. In stillanother embodiment, the composition may be made of an amine and an epoxy(such as a composition comprising at least one diamine and at least oneepoxy resin as disclosed herein). In other embodiments, the compositionmay comprise varying von Mises strain results, and may be made ofdiffering materials.

In still another embodiment of the disclosure, a method of forming acomposition having increased von Mises strain is provided. The methodmay comprise combining an amine and an epoxy (such as combining at leastone diamine and at least one epoxy resin as disclosed herein) in orderto increase distortional load and/or lower dilatation load. In anotherembodiment, the method may further comprise the step of combiningvariations of amines and epoxies (such as combining variations ofdiamines and/or variations of epoxy resins as disclosed herein) in orderto form the composition with increased distortional load, with lowereddilatation load, and with increased von Mises strain. In still anotherembodiment, the von Mises strain of the formed composition may be atleast 0.300. In yet another embodiment, the von Mises strain of theformed composition may be at least 0.400. In other embodiments, varyingsteps may be utilized to provide increased von Mises strain, and theresultant von Mises strain may be in differing amounts.

The disclosure may provide composites having increased distortionaldeformation, and/or decreased dilatation load, which may provideunexpected increases in von Mises strain results and unexpected enhancedcomposite mechanical performances over one or more of the prior artcomposites. These advantages in mechanical performances may providecomposites which are of increased strength, lower weight, and/or havingother advantages in one or more properties over one or more of the priorart composites.

It should be understood, of course, that the foregoing relates toexemplary embodiments of the disclosure and that modifications may bemade without departing from the spirit and scope of the disclosure asset forth in the following claims.

1. A composition having a von Mises strain of at least 0.300 comprisingat least one diamine and at least one epoxy resin, which collectivelyhave the von Mises strain of at least 0.300, the composition comprisingone of the following groups: (1) a Bisphenol F based tri-functionalnovolac epoxy resin and a 4,4′ bis(3-aminophenoxy) diphenylsulfone; (2)a Bisphenol F based tri-functional novolac epoxy resin and a 3,3′diaminodiphenylsulfone; (3) a Bisphenol F based tri-functional novolacepoxy resin and a 1,3 bis(3-aminophenoxy) benzene; (4) a diglycidyl α,α′-bis(4-hydroxyphenyl)-p-diisopropylbenzene and a 4,4′bis(3-aminophenoxy) diphenylsulfone; (5) a 1,3 bis(4-aminophenoxy)-2,2dimethylpropane and a diglycidyl ether of Bisphenol-A; or (6) a 1,3bis(3-aminophenoxy)-2,2 dimethylpropane and a diglycidyl ether ofBisphenol-A.
 2. The composition of claim 1 wherein the von Mises strainof said composition is at least 0.400.
 3. The composition of claim 1wherein the composition comprises the Bisphenol F based tri-functionalnovolac epoxy resin and the 4,4′ bis(3-aminophenoxy) diphenylsulfone. 4.The composition of claim 3 wherein the von Mises strain of thecomposition ranges from substantially 0.322 with a diamine weightpercent content of substantially 41% to substantially 0.342 with thediamine weight percent content of substantially 65%, wherein saiddiamine comprises said 4,4′ bis(3-aminophenoxy) diphenylsulfone.
 5. Thecomposition of claim 4 wherein the substantially 41% diamine weightpercent content composition comprises a substantially 1:1 stoichiometryratio.
 6. The composition of claim 1 wherein the composition comprisesthe Bisphenol F based tri-functional novolac epoxy resin and the 3,3′diaminodiphenylsulfone.
 7. The composition of claim 6 wherein the vonMises strain of said composition ranges up to substantially 0.345 withthe diamine weight percent content being 52%, wherein said at least onediamine comprises said 3,3′ diaminodiphenylsulfone.
 8. The compositionof claim 1 wherein the composition comprises the Bisphenol F basedtri-functional novolac epoxy resin and the 1,3 bis(3-aminophenoxy)benzene.
 9. The composition of claim 8 wherein the von Mises strain ofthe composition ranges from substantially 0.313 with the diamine weightpercent content of substantially 32% to substantially 0.37 with thediamine weight percent content of substantially 56%, wherein said atleast one diamine comprises said 1,3 bis(3-aminophenoxy) benzene. 10.The composition of claim 9 wherein the substantially 32% diamine weightpercent content composition comprises a substantially 1:1 stoichiometryratio.
 11. The composition of claim 1 wherein the composition comprisesthe diglycidyl α, α′-bis(4-hydroxyphenyl)-p-diisopropylbenzene and the4,4′ bis(3-aminophenoxy) diphenylsulfone.
 12. The composition of claim11 wherein the von Mises strain of the composition ranges fromsubstantially 0.41 with a diamine weight percent content ofsubstantially 24% to substantially 0.42 with the diamine weight percentcontent of substantially 32%, wherein said at least one diaminecomprises said 4,4′ bis(3-aminophenoxy) diphenylsulfone.
 13. Thecomposition of claim 12 wherein the substantially 32% diamine weightpercent content composition comprises a substantially 1:1 stoichiometryratio.
 14. The composition of claim 1 wherein the composition comprisesthe 1,3 bis(4-aminophenoxy)-2,2 dimethylpropane and the diglycidyl etherof Bisphenol-A.
 15. The composition of claim 14 wherein the compositioncomprises a substantially 1:1 stoichiometric ratio of substantially 30%by weight of said 1,3 bis(4-aminophenoxy)-2,2 dimethylpropane substancewith substantially 70% by weight of said diglycidyl ether of Bisphenol-Ato yield the von Mises strain of substantially 0.31.
 16. The compositionof claim 1 wherein the composition comprises the 1,3bis(3-aminophenoxy)-2,2 dimethylpropane and the diglycidyl ether ofBisphenol-A.
 17. The composition of claim 16 wherein the compositioncomprises a substantially 1:1 stoichiometric ratio of substantially 30%by weight of said 1,3 bis(3-aminophenoxy)-2,2 dimethylpropane substancewith substantially 70% by weight of said diglycidyl ether of Bisphenol-Ato yield the von Mises strain of substantially 0.32.
 18. The compositionof claim 1 wherein the composition consists of one diamine and one epoxyresin from among the groups of (1), (2), (3), (4), (5), or (6).